This invention relates to treating crude oil. In one of its aspects this invention relates to removing mineral sediment from crude oil. In another of its aspects this invention relates to the use of filtration for removal of mineral sediment from treated crude oil. In still another of its aspects this invention relates to the removal of mineral sediment from a system for treating crude oil.
In the treating of crude oil to recover a maximum of useable hydrocarbons a problem arises in determining the most economical and ecologically sound means for disposing of mineral sediment or sludge that is removed from the crude oil during processing.
In a typical operation crude oil is desalted or demineralized by contacting heated crude oil with water or water containing about 4 to 5 percent soda ash in solution and an emulsion breaking compound with passage of the contact mixture through a suitably baffled and/or agitated vessel to allow removal of mineral contaminant into a separated water phase while an at least partially demineralized oil phase is separately removed for further treatment. Further treatment usually involves a fractionation operation which produces a residue, a topped crude oil containing mineral sediment that had not been previously removed. Normally this topped crude oil is subjected to hydrodesulfurization followed by further fractionation of the hydrodesulfurized product. The sediment contained in the topped crude is deleterious to the hydrodesulfurization catalyst and is, therefore, usually removed by filtering the topped crude before passing the oil to the hydrodesulfurzation process.
In a typical operation, as is well known in the prior art, this sediment collected on the filtering apparatus is removed from the filter by backwashing with a stream of topped crude oil which is charged along with the sediment removed from the filter into the distillation apparatus used to fractionate the hydrodesulfurized, topped crude oil that was prepared from the topped crude oil that passed through the filter. In other words, this mineral sediment has in the past been removed from the process streams only to bypass the hydrodesulfurization unit thereby protecting the catalyst.
The present invention provides an ecologically sound process by which the sediment does not find its way back into the stream of product oil but is, instead, removed as waste from the system.
It is therefore an object of this invention to provide a method for removing mineral sediment from a topped crude oil. It is another object of this invention to provide means for disposing of sediment retained during filtering of a topped crude oil stream that does not entail recontaminating the topped crude oil stream from which the sediment was removed.
Other aspects, objects and the various advantages of this invention will become apparent from study of this specification, the drawing, and the appended claims.